What they were created from and when
The substance from which Allah, the Most Exalted, created angels is light. It is narrated on the authority of `Aa'ishah that the Messenger of Allah said: "The angels were created from light, the jinn were created from smokeless fire, and Adam was created from that which has been described to you (i.e. in the Quran, which is clay)." [Muslim]
Prophet Muhammad did not explain what light this is that they were created from. Hence we cannot indulge in trying to say more about this matter, because it is the matter of the unseen concerning which no further clarification has been narrated, apart from this Hadeeth (narration).
We do not know when the angels were created, for Allah has not informed us about that. But we do know that they were created before Adam the father of mankind. Allah has told us that He informed the angels that He was going to create a Khaleefah (vicegerent) on earth. Almighty Allah Says in the Noble Quran (what means):
{And [mention, O Muhammad], when your Lord said to the angels, 'Indeed, I will make upon the earth a successive authority.} [Quran 2:30]
Allah also Says (what means): {And when I have proportioned him and breathed into him of My soul, then fall down to him in prostration.} [Quran 15:29]
Seeing the angels
Because the angels have bodies of light which are of low density, mankind cannot see them, especially since Allah has not given our eyes the ability to see them.
No one has seen the angels in their true form apart from Prophet Muhammad . He saw Jibreel (angel Gabriel) twice in the form in which Allah created him.
On the other hand, different texts indicate that human beings were able to see the angels in human form. An example for this is the long Hadeeth (narration), 'Umar Ibn Al-Khattab said: "One day while we were sitting with the Messenger of Allah there appeared before us a man whose clothes were exceedingly white and whose hair was exceedingly black; no signs of journeying were to be seen on him and none of us knew him. He walked up and sat down by the Prophet (). Resting his knees against his and placing the palms of his hands on his thighs, he said: 'O Muhammad, tell me about Islam…..'"
After asking the Prophet other questions, the visitor left and the Prophet said to 'Umar : "O 'Umar, do you know who the questioner was?" 'Umar said: 'Allah and His Messenger know best'. He said: 'He was Jibreel (Gabriel); he came to teach you your religion.'" [Muslim]
(2) Their great physical size
Allah, the Most Exalted, Says concerning the angels of Hell (what means):
"O you who have believed, protect yourselves and your families from a Fire whose fuel is people and stones, over which are [appointed] angels, harsh and severe; they do not disobey Allah in what He commands them but do what they are commanded." [Quran 66:6]
It will be sufficient in this regard to quote the narrations which speak of two noble angels.
The great size of Jibreel
The Messenger of Allah saw Jibreel twice in the angelic form in which Allah created him. These two occasions are mentioned in the verse (which means):
"And he [i.e. Muhammad] has already seen him [i.e. Jibreel] in the clear horizon." [Quran 81:23]
And the verse (which means):
"And he certainly saw him in another descent. At the Lote Tree of the Utmost Boundary. Near it is the Garden of Refuge [i.e. Paradise]." [Quran 53:13-15]
That was when he was taken up to the highest heaven during his miraculous ascension to heaven.
It is narrated that `Aa'ishah said: "I asked the Messenger of Allah about these two verses. He said, "That is Jibreel; I never saw him in the form in which Allah created him except on these two occasions. I saw him descending from the heavens, with his huge size filling the horizon between the heaven and the earth." [Muslim]
`Aa'ishah was asked about the verse (which means): "Then he [Jibreel] approached and descended." [Quran 53:8]
She said, "That is Jibreel. He used to come to him (the Prophet ) in human form, but on this occasion he came in his real form, and he filled the horizons of the sky." [Muslim]
It is narrated that 'Abdullaah Ibn Mas'ood said: "Muhammad saw Jibreel with six hundred wings."[Al-Bukhari]
He (Ibn Mas'ood) said concerning the verse (which means):
{He certainly saw of the greatest signs of his Lord.} [Quran 53:18]
"This means green cushions, filling the horizons."[Al-Bukhari]
These cushions that filled the horizons were what Jibreel was seated upon. Ibn Mas'ood also said, "The Prophet of Allah saw Jibreel with his own eyes, on a cushion which filled the space between heaven and earth."
'Abdullah Ibn Mas'ood said: "The Messenger of Allah saw Jibreel in his true form. He had six hundred wings, each of which filled the horizon, and there were multi-coloured pearls and rubies falling from his wings." [Ahmad]
Almighty Allah Says, describing Jibreel (what means):
"…Indeed, it [i.e. the Quran] is a word [conveyed by] a noble messenger [i.e. Jibreel]. [Who is] possessed of power and with the Owner of the Throne, secure [in position]. Obeyed there [in the heavens] and trustworthy."[Quran 81:19-21]
What is meant by the "most honourable messenger" here is Jibreel, and the Lord of the Throne is the Lord of Glory, may He be glorified.